Railway truck motor suspension

ABSTRACT

A rail vehicle drive assembly having an a-c motor whose rotor is rigidly coupled to and overhung from the pinion of a gear train operably connected to drive the axle. The motor stator is likewise integrally overhung from a gear train housing journaled to the axle, and the combination is flexibly mounted to the vehicle truck. Advantages include the obviation of the flexible couplings, rotor bearings, and axle support of the motor, by direct connection thereto.

United States Patent 11 1 1111 3,792,666

Coho et al. 1 Feb. 19, 1974 [54] RAILWAY TRUCK MOTOR SUSPENSION2,742,864 4/1956 Envart 105/136 Inventors: Owen C. Coho; Malcolm W.Waite, i321??? 2x322 both of Erie, Pa. 3,286,656 11/1966 Lich 133 )4[73] Assignee: General Electric Company, Erie, Pa.

Primary Examiner-Gerald M. Forlenza [22] Flled' 1972 AssistantExaminer-Howard Beltran [21] Appl. N0.: 278,002 Attorney, Agent, orFirm-Dana F. Bigelow; Walter C.

Bernkof [52] US. Cl 105/136, 105/108, 105/139,

105/140 [57] ABSTRACT Int. A rail vehicle drive assembl y having an a-cmotor [58] held of Search 105/133 F whose rotor is rigidly coupled toand overhung from 105/139 /62 65 F the pinion of a gear train operablyconnected to drive the axle. The motor stator is likewise integrallyover- [56] References C'ted hung from a gear train housing joumaled tothe axle, UNITED STATES PATENTS and the combination is flexibly mountedto the vehicle 3,152,558 10/1964 Mueller 105/133 truck. Advantagesinclude the obviation of the flexible 2,023,846 12/1935 Levin couplings,rotor bearings, and axle support of the mo- 556393 3/1396 g tor, bydirect connection thereto. 2,023,856 12/1935 Sanders... 2,039,513 5/1936Baker 180/65 F 9 Claims, 2 Drawing Figures Mme F PAIENIEB FEB l 9 I974SHEET 2 BF 2 I RAILWAY TRUCK MOTOR SUSPENSION BACKGROUND OF THEINVENTION This invention relates generally to rail vehicular drivesystems and more particularly to the electric motor drive of a vehicleaxle through a gear train.

Railway vehicles such as locomotives and transit cars are commonlypropelled by an electric motor driving an axle through spur reductiongearing. The motor is mounted between the axle wheels in parallel driverelation to, and offset from the axle, either upwardly or longitudinallyor both, with support connection made from the motor to the vehicletruck structure.

Generally, in locomotive applications a large heavy duty traction motoris mounted directly to the axle by sleeve bearings and to the truck by aresilient nose suspension. Overhung from the motor armature is a piniongear operably engaging a spur gear to drive the axle. In such a systemthe principal support of the motor is provided by the sleeve bearings,which are quite adequate at low and moderate speeds.

ln propulsion systems adapted for higher speeds, such as in transit carapplications, the sleeve bearings are undesirable for several reasons,most important of which is their inability to dissipate the generatedheat, and to withstand the axial thrust produced by reaction to helicalgearing. Replacement of spur gears with helical gears was introduced toprevent excessive noise at high speeds. Also contributing to the problemof uncle sirable noise is that of gear misalignment occasioned by theheavy loads. Thus, at higher speeds, positive location of gearing isrequired to obtain the desired preci sion in the gear train.

The requirements encountered in high speed systems are commonly met bythe use of anti-friction bearings to replace the aforementioned sleevebearings. In addition to solving the problems discussed hereinabove, theanti-friction bearings are much lighter and are therefore more readilyadapted to use on high speed vehicles. Anti-friction bearings are nowbeing employed in place of sleeve bearings on some locomotive drivesysterns, thereby alleviating some of the bearing problems discussedhereinabove which are occasional by high speed operation. Generally,they are placed one on each end of the motor, as are the sleevebearings. Such a mounting however, must allow for the flexing of theaxle, a consideration which may be serious when the bearings are widelyspaced and high loads are involved.

In high speed transit applications, such an approach is thereforeavoided, and a closer bearing placement is provided. Typically, a pairof tapered roller bearings are employed to rotatably mount the gearhousing structure to the axle, with the housing being rotationallystabilized by flexible attachment to the vehicle truck. Motor support isprovided by a similar attachment to the truck, and possibly byadditional attachment to the gear housing, the axle, or both. Unlike theaforementioned overhung pinion arrangement, wherein the pinion is notjoumaled but forms an integral extension of the joumaled rotor, both thepinion and armature are joumaled, with each one being mounted betweenits own pair of bearings. Bearing alignment is critical with such adesign and if attained, it is difficult to maintain; therefore, aflexible coupling is provided between the armature and the pinion toallow for misalignment of the two shafts.

Although the flexible coupling may provide the answer to themisalignment phenomena, it is the cause of other difficulties which maymake its use undesirable. Its proper assembly is critical, and if notperformed correctly, a failure is likely to occur. Furthermore, thecoupling must be disassembled whenever the motor armature is removed formaintenance purposes, a fact that increases the likelihood of itssubsequently being assembled incorrectly. Improper assembly isoccasioned by improper fit of the hubs on the respective shafts(typically splined or tapered) or by improper joining of the hubs.

It is therefore an object of this invention to provide an improvedmotive drive arrangement for high speed rail vehicles.

Another object of this invention. is the provision in a high speed railvehicle for a light weight drive assembly to be coupled to the vehicleaxle.

Yet another object of this invention is the provision for positivelocation of precision gears coupling a traction motor to the axle of arail vehicle.

Still another object of this invention is the provision for theelimination of a flexible coupling between the motor rotor and the drivepinion of a rail vehicle drive system.

A further object of this invention is the provision for a single pair ofhearings to support both the motor rotor and the associated pinion ofthe drive system.

Yet another object of this invention is the provision for flexibilitybetween a rail vehicle axle and its associated truck.

Still another object of this invention is the provision for a high speedrail vehicle drive assembly which is economical to manufacture, as wellas functional and durable in use.

These objects and other features and advantages be come more readilyapparent upon reference to the following description when taken inconjunction with the appended drawings.

SUMMARY OF THE INVENTION This invention achieves the stated objectivesby overhanging a traction motor from a gear drive assembly joumaled tothe axle of a traction vehicle. The motor stator is rigidly connected tothe gear housing, and the motor rotor is integrally connected to andoverhung from the high speed pinion gear. Bearings straddle the piniongear and comprise the only support for the motor rotor cantilevered fromthe pinion.

Such an arrangement is made possible by the use of a relatively smalllight weight ac induction motor for providing motive power to thevehicle. Flexibility is provided between the vehicle truck and therelatively rigid combination of motor, gear unit, and axle, by aflexible coupling therebetween, connection being made to either themotor or the gear housing. No flexibility is required between the axleand the motor as in the case of a d-c motor having a commutator andbrushes.

The subject drive assembly is an integral unit, which is simpler,lighter weight, less expensive and much more compact than conventionalarrangements.

In the drawings as hereinafter described a preferred embodiment isdepicted; however, various other modifications and alternateconstructions can be made thereto without departing from the true spiritand scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a top plan view of thepropulsion drive arrangement as constructed in accordance with theprinciples of the invention.

FIG. 2 is a partial cross section thereof showing the internal structureembodied therein.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now made to FIG. 1wherein the subject drive arrangement is shown generally at 10. A truckframe 11 is supported by a pair of axles l2 and 13, (only one shown)each of which is provided with a pair of flanged wheels 14 and 16 spacedappropriately for frictional engagement with spaced tracks (not shown).Mounted on the truck frame 11 is a car body (not shown) cushioned in aconventional manner, such as by springs, pads, or the like, disposedbetween the truck and body. Journal boxes 17 and 18 are commonlyprovided to allow for rotation of the axles within the truck frame, andgenerally provide a degree of resiliency therebetween to allow forvibration of the axles relative to the truck frame. As will be shownhereinafter a considerable space savings inherent in the subject designarrangement allows application to trucks having either outside or insidejournal suspension systems. Furthermore, the additional space allows forthe installation of a friction brake 19, such as a disc-type brake to beoperably connected to the axle in the manner shown.

Motive power is provided to the axle 12 by an electric motor 21operating a gear drive system 22 mechan ically connected to the axle.Rigid interconnection is made both between the axle and gear drivesystem and between the gear drive and the motor 21. A resilientinterconnection 23 is provided between the motor gear drive combinationand the truck frame 11, the connection being made at either the gear boxas shown, or alternatively at the motor.

For a more detailed discussion of the assembly reference is now made toFIG. 2 wherein the connection and support elements are more clearlyshown.

The sole connection made between the drive assembly and the axle 12 isby a hub 24 which is rigidly secured to the axle proximate its one end.The manner of attachment is typically accomplished by shrinking the hubon the axle to form an integral unit. Projecting radially outward fromthe hub is a'flange 26 to which is attached a gear 27 of theconventional type, attachment being made by a plurality of studs 28placed in arcuately spaced holes formed in the flange 26. This spur geardirectly drives the axle by operational engagement with a meshing piniongear 29. Although not shown in the preferred embodiment, one or morereduction gear phases may be provided between the high speed pinion 29and the spur gear 27. A gear housing assembly 30 surrounds the geartrain and is attached to the hub 24 as will hereinafter be described.

Motive power is delivered directly to the pinion 29 by the motor rotor31 whose shaft 32 is disposed in parallel relationship with the vehicleaxle 12. This invention is facilitated by the use of an a-c motor, andpreferably an a-c motor of the induction type, wherein the relativelylight weight, high speed rotor can be overhung from its associatedpinion gear. A rigid connection is provided between the rotor shaft 32and the pinion 29, with the rotor being overhung from the pinion in acantilever fashion. A preferred arrangement is to have an integral shaft33 as shown, wherein the rotor body 34 is shrunk-fit to the rotor endthereof.

Support for both the pinion 29 and the rotor 31 is provided by a singlepair of bearings 36 and 37, those shown being of the tapered rollertype, disposed one on each end of the pinion so as to straddle it. Theassociated bearing outer races 38 and 39 are integral with the gearhousing structure 30 as shown.

The above described bearing arrangement provides cantilever support forthe overhung motor rotor which transmits pure torque, and reactionsupport to the pinion which is subjected to heavy radial loads from thespur gear 27. The requirement for separate pairs of bearings for each ofthe rotor and pinion, as is required in conventional systems, is thuseliminated. Even more important, since the shafts form an integral unitand are supported by a single pair of bearings, the problem of axialalignment is eliminated and the relative flexibility, which washeretofore provided by a troublesome flexible coupling, can also beeliminated. Thus, a considerable space savings is made as well as thereducing of maintenance problems occasioned by flexible couplings andbearing and their associated components such as seals, housings,sleeves, bearing nuts, etc.

In addition to providing support for the motor rotor 31, the gearhousing assembly 30 also provides structural support for the motorstator 41. The stator 41 is rigidly secured to the housing assembly 30so as to be completely supported thereby. Various methods of attachmentmay be used; however, the preferred method is that of forming anintegral shell as shown, by the use of bridging support element 42.Assembly and disassembly is facilitated by the securing of articulatedcomponents 43 and 44 by means such as by studs 46.

Thus, the motor electrical air gap is maintained between the rotor andstator by the rigid connection to the pinion gear and associatedhousing, respectively, which provide complete structural supporttherefor. As stated hereinbefore the pinion gear derives support from apair of bearings disposed in the gear housing assembly 30. This assemblyin turn is journaled to the hub 24 by a second pair of tapered rollerbearings 47 and 48. The axial spacing thereof is sufficiently great toensure proper support for the moment arm forces of the cantileveredmotor, and yet narrow enough to not be seriously affected by a flexingof the axle 12. A pair of associated seals 49 and 51 are providedbetween the housing 42 and hub 24 to ensure the integrity of the geartrain.

Torque reaction of the housing to motive force is offset by theresilient interconnection 23 secured to the truck frame 11. Theflexibility inherent therein allows for relative movement of the entireassembly with respect to the truck, and comprises the sole means ofresiliency between the motor-gear assembly and the truck. The integralassembly is thus simple, light and compact, and lends itself toapplication on high speed light weight transit systems.

What we claim as new and desire to secure by Letters Patent of theUnited States are:

1. A drive assembly for rail vehicles of the type having a body mountedon a truck having a journaled axle and associated rail engaging wheels,the assembly comprising:

a. gear drive means connected to the axle for operative rotationthereof;

b. a housing encasing said gear drive means and rotatably mounted to theaxle;

c. a drive motor operably connected to said gear drive means, the statorof said motor deriving its sole support from a rigid connection betweenits one end thereof and said housing, and the rotor thereof deriving itssole support from a rigid coupling of its shaft to said gear drivemeans; and

d. a connection between said housing and the truck,

said connection providing support for said housing and a reaction to thedriving torque said connection being substantially in the plane of thegear drive means.

2. A drive assembly as set forth in claim 1 wherein said gear drivemeans includes a pinion gear with which the shaft of said rotor isaxially'aligned and rigidly connected to so as to form an extensionthereof and derive support therefrom.

3. A drive assembly as set forth in claim 2 where the pinion gear andthe shaft of said rotor comprise an integrally formed unit.

4. A drive assembly as set forth in claim 2 and including journal meansdisposed in said housing for rotational engagement with and support ofsaid pinion gear.

5. A drive assembly as set forth in claim 4 wherein said journal meanscomprises a pair of tapered roller bearings axially spaced proximateopposite ends of said pinion gear.

6. A drive assembly as set forth in claim ll wherein said gear drivemeans includes a spur gear rigidly mounted to the axle and drivablyengaged with said spur gear.

7. A drive assembly as set forth in claim 11 wherein said housing isrotatably mounted to the axle by a pair of axially spaced rollerbearings disposed therebetween.

8. A drive assembly as set forth in claim 1 wherein said housing and thestator of said motor comprise a single integral unit.

9. A drive assembly as set forth in claim 1 wherein said gear drivemeans is rigidly connected to the axle and further wherein saidconnection between said housing and the truck is flexible so as toprovide resiliency therebetween.

1. A drive assembly for rail vehicles of the type having a body mountedon a truck having a journaled axle and associated rail engaging wheels,the assembly comprising: a. gear drive means connected to the axle foroperative rotation thereof; b. a housing encasing said gear drive meansand rotatably mounted to the axle; c. a drive motor operably connectedto said gear drive means, the stator of said motor deriving its solesupport from a rigid connection between its one end thereof and saidhousing, and the rotor thereof deriving its sole support from a rigidcoupling of its shaft to said gear drive means; and d. a connectionbetween said housing and the truck, said connection providing supportfor said housing and a reaction to the driving torque said connectionbeing substantially in the plane of the gear drive means.
 2. A driveassembly as set forth in claim 1 wherein said gear drive means includesa pinion gear with which the shaft of said rotor is axially aligned andrigidly connected to so as to form an extension thereof and derivesupport therefrom.
 3. A drive assembly as set forth in claim 2 where thepinion gear and the shaft of said rotor comprise an integrally formedunit.
 4. A drive assembly as set forth in claim 2 and including journalmeans disposed in said housing for rotational engagement with andsupport of said pinion gear.
 5. A drive assembly as set forth in claim 4wherein said journal means comprises a pair of tapered roller bearingsaxially spaced proximate opposite ends of said pinion gear.
 6. A driveassembly as set forth in claim 1 wherein said gear drive means includEsa spur gear rigidly mounted to the axle and drivably engaged with saidspur gear.
 7. A drive assembly as set forth in claim 1 wherein saidhousing is rotatably mounted to the axle by a pair of axially spacedroller bearings disposed therebetween.
 8. A drive assembly as set forthin claim 1 wherein said housing and the stator of said motor comprise asingle integral unit.
 9. A drive assembly as set forth in claim 1wherein said gear drive means is rigidly connected to the axle andfurther wherein said connection between said housing and the truck isflexible so as to provide resiliency therebetween.